BRITISH SPONGIAD^E. 325 



granulated gelatinous substance semi-transparent and re- 

 taining its red colour. 



34. Isodictya Edwardii, Bowerbank. 



Sponge. Sessile, parasitical, coating. Surface ^uneven, 

 hispid. Oscula inconspicuous, simple, dispersed. 

 Pores inconspicuous. Dermal membrane pellucid, 

 sparingly spiculous ; tension spicula acuate, long, and 

 slender ; retentive spicula bidentate equi-anchorate, 

 slender, minute, few in number. Skeleton. Diffusive 

 and irregular ; primary lines multispiculous ; secon- 

 dary lines very irregular, occasionally bi or trispicu- 

 lous ; spicula acuate, rather long. Interstitial mem- 

 branes. Tension spicula rather abundant, acuate, 

 variable in size ; retentive spicula same as those of 

 the dermal membrane, very few in number. Gem- 

 mules membranous, aspiculous. 



Colour. Dried, ochreous yellow. 



Habitat. Banff, Scotland, Mr. T. Edward. 



Examined. In the dried state. 



This sponge coats the stems of Tubularia for the length 

 of seven inches, at no part exceeding two lines in thick- 

 ness. Its general aspect in the dried state is rough and 

 irregular in consequence of the prominent hispidation of 

 its surface, produced by the prolongation of the primary 

 lines of the skeleton beyond the dermal membrane, fre- 

 quently to the extent of the length of two or three times 

 that of a spiculum. The oscula are not visible without the 

 aid of a lens of an inch focus. The construction of the 

 skeleton is very irregular and diffusive, and the secondary 

 lines especially, and to such an extent as to frequently 

 render it difficult to decide whether they are really secon- 

 dary skeleton lines or dispersed skeleton spicula. The 

 skeleton spicula are regularly acuate and rather slender. 

 The retentive spicula are not visible in a fragment of the 



